/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.feilong.lib.beanutils;

import java.beans.IndexedPropertyDescriptor;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.beanutils.DynaBean;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.feilong.lib.beanutils.expression.Resolver;

/**
 * <p>
 * JavaBean property population methods.
 * </p>
 *
 * <p>
 * This class provides implementations for the utility methods in
 * {@link BeanUtils}.
 * Different instances can be used to isolate caches between classloaders
 * and to vary the value converters registered.
 * </p>
 *
 * @version $Id$
 * @see BeanUtils
 * @since 1.7
 */

public class BeanUtilsBean{

    /** The Constant log. */
    private static final Logger                                 LOGGER               = LoggerFactory.getLogger(BeanUtilsBean.class);

    // ------------------------------------------------------ Private Class Variables

    /**
     * Contains <code>BeanUtilsBean</code> instances indexed by context classloader.
     */
    private static final ContextClassLoaderLocal<BeanUtilsBean> BEANS_BY_CLASSLOADER = new ContextClassLoaderLocal<BeanUtilsBean>(){

                                                                                         // Creates the default instance used when the context classloader is unavailable
                                                                                         @Override
                                                                                         protected BeanUtilsBean initialValue(){
                                                                                             return new BeanUtilsBean();
                                                                                         }
                                                                                     };

    /**
     * Gets the instance which provides the functionality for {@link BeanUtils}.
     * This is a pseudo-singleton - an single instance is provided per (thread) context classloader.
     * This mechanism provides isolation for web apps deployed in the same container.
     *
     * @return The (pseudo-singleton) BeanUtils bean instance
     */
    public static BeanUtilsBean getInstance(){
        return BEANS_BY_CLASSLOADER.get();
    }

    /**
     * Sets the instance which provides the functionality for {@link BeanUtils}.
     * This is a pseudo-singleton - an single instance is provided per (thread) context classloader.
     * This mechanism provides isolation for web apps deployed in the same container.
     *
     * @param newInstance
     *            The (pseudo-singleton) BeanUtils bean instance
     */
    public static void setInstance(final BeanUtilsBean newInstance){
        BEANS_BY_CLASSLOADER.set(newInstance);
    }

    // --------------------------------------------------------- Attributes

    /** Used to perform conversions between object types when setting properties */
    private final ConvertUtilsBean  convertUtilsBean;

    /** Used to access properties */
    private final PropertyUtilsBean propertyUtilsBean;

    // --------------------------------------------------------- Constuctors

    /**
     * <p>
     * Constructs an instance using new property
     * and conversion instances.
     * </p>
     */
    public BeanUtilsBean(){
        this(new ConvertUtilsBean(), new PropertyUtilsBean());
    }

    /**
     * <p>
     * Constructs an instance using given conversion instances
     * and new {@link PropertyUtilsBean} instance.
     * </p>
     *
     * @param convertUtilsBean
     *            use this <code>ConvertUtilsBean</code>
     *            to perform conversions from one object to another
     *
     * @since 1.8.0
     */
    public BeanUtilsBean(final ConvertUtilsBean convertUtilsBean){
        this(convertUtilsBean, new PropertyUtilsBean());
    }

    /**
     * <p>
     * Constructs an instance using given property and conversion instances.
     * </p>
     *
     * @param convertUtilsBean
     *            use this <code>ConvertUtilsBean</code>
     *            to perform conversions from one object to another
     * @param propertyUtilsBean
     *            use this <code>PropertyUtilsBean</code>
     *            to access properties
     */
    public BeanUtilsBean(final ConvertUtilsBean convertUtilsBean, final PropertyUtilsBean propertyUtilsBean){
        this.convertUtilsBean = convertUtilsBean;
        this.propertyUtilsBean = propertyUtilsBean;
    }

    // --------------------------------------------------------- Public Methods

    /**
     * <p>
     * Clone a bean based on the available property getters and setters,
     * even if the bean class itself does not implement Cloneable.
     * </p>
     *
     * <p>
     * <strong>Note:</strong> this method creates a <strong>shallow</strong> clone.
     * In other words, any objects referred to by the bean are shared with the clone
     * rather than being cloned in turn.
     * </p>
     *
     * @param bean
     *            Bean to be cloned
     * @return the cloned bean
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InstantiationException
     *             if a new instance of the bean's
     *             class cannot be instantiated
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     * @throws NoSuchMethodException
     *             if an accessor method for this
     *             property cannot be found
     */
    public Object cloneBean(final Object bean)
                    throws IllegalAccessException,InstantiationException,InvocationTargetException,NoSuchMethodException{
        if (LOGGER.isDebugEnabled()){
            LOGGER.debug("Cloning bean: " + bean.getClass().getName());
        }
        Object newBean = null;
        if (bean instanceof DynaBean){
            newBean = ((DynaBean) bean).getDynaClass().newInstance();
        }else{
            newBean = bean.getClass().newInstance();
        }
        getPropertyUtils().copyProperties(newBean, bean);
        return (newBean);

    }

    /**
     * <p>
     * Copy property values from the origin bean to the destination bean
     * for all cases where the property names are the same. For each
     * property, a conversion is attempted as necessary. All combinations of
     * standard JavaBeans and DynaBeans as origin and destination are
     * supported. Properties that exist in the origin bean, but do not exist
     * in the destination bean (or are read-only in the destination bean) are
     * silently ignored.
     * </p>
     *
     * <p>
     * If the origin "bean" is actually a <code>Map</code>, it is assumed
     * to contain String-valued <strong>simple</strong> property names as the keys, pointing at
     * the corresponding property values that will be converted (if necessary)
     * and set in the destination bean. <strong>Note</strong> that this method
     * is intended to perform a "shallow copy" of the properties and so complex
     * properties (for example, nested ones) will not be copied.
     * </p>
     *
     * <p>
     * This method differs from <code>populate()</code>, which
     * was primarily designed for populating JavaBeans from the map of request
     * parameters retrieved on an HTTP request, is that no scalar->indexed
     * or indexed->scalar manipulations are performed. If the origin property
     * is indexed, the destination property must be also.
     * </p>
     *
     * <p>
     * If you know that no type conversions are required, the
     * <code>copyProperties()</code> method in {@link PropertyUtils} will
     * execute faster than this method.
     * </p>
     *
     * <p>
     * <strong>FIXME</strong> - Indexed and mapped properties that do not
     * have getter and setter methods for the underlying array or Map are not
     * copied by this method.
     * </p>
     *
     * @param dest
     *            Destination bean whose properties are modified
     * @param orig
     *            Origin bean whose properties are retrieved
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws IllegalArgumentException
     *             if the <code>dest</code> or
     *             <code>orig</code> argument is null or if the <code>dest</code>
     *             property type is different from the source type and the relevant
     *             converter has not been registered.
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     */
    public void copyProperties(final Object dest,final Object orig) throws IllegalAccessException,InvocationTargetException{
        // Validate existence of the specified beans
        if (dest == null){
            throw new IllegalArgumentException("No destination bean specified");
        }
        if (orig == null){
            throw new IllegalArgumentException("No origin bean specified");
        }
        if (LOGGER.isDebugEnabled()){
            LOGGER.debug("BeanUtils.copyProperties(" + dest + ", " + orig + ")");
        }

        // Copy the properties, converting as necessary
        if (orig instanceof DynaBean){
            final DynaProperty[] origDescriptors = ((DynaBean) orig).getDynaClass().getDynaProperties();
            for (DynaProperty origDescriptor : origDescriptors){
                final String name = origDescriptor.getName();
                // Need to check isReadable() for WrapDynaBean
                // (see Jira issue# BEANUTILS-61)
                if (getPropertyUtils().isReadable(orig, name) && getPropertyUtils().isWriteable(dest, name)){
                    final Object value = ((DynaBean) orig).get(name);
                    copyProperty(dest, name, value);
                }
            }
        }else if (orig instanceof Map){
            @SuppressWarnings("unchecked")
            final
            // Map properties are always of type <String, Object>
            Map<String, Object> propMap = (Map<String, Object>) orig;
            for (final Map.Entry<String, Object> entry : propMap.entrySet()){
                final String name = entry.getKey();
                if (getPropertyUtils().isWriteable(dest, name)){
                    copyProperty(dest, name, entry.getValue());
                }
            }
        }else /* if (orig is a standard JavaBean) */ {
            final PropertyDescriptor[] origDescriptors = getPropertyUtils().getPropertyDescriptors(orig);
            for (PropertyDescriptor origDescriptor : origDescriptors){
                final String name = origDescriptor.getName();
                if ("class".equals(name)){
                    continue; // No point in trying to set an object's class
                }
                if (getPropertyUtils().isReadable(orig, name) && getPropertyUtils().isWriteable(dest, name)){
                    try{
                        final Object value = getPropertyUtils().getSimpleProperty(orig, name);
                        copyProperty(dest, name, value);
                    }catch (final NoSuchMethodException e){
                        // Should not happen
                    }
                }
            }
        }

    }

    /**
     * <p>
     * Copy the specified property value to the specified destination bean,
     * performing any type conversion that is required. If the specified
     * bean does not have a property of the specified name, or the property
     * is read only on the destination bean, return without
     * doing anything. If you have custom destination property types, register
     * {@link Converter}s for them by calling the <code>register()</code>
     * method of {@link ConvertUtils}.
     * </p>
     *
     * <p>
     * <strong>IMPLEMENTATION RESTRICTIONS</strong>:
     * </p>
     * <ul>
     * <li>Does not support destination properties that are indexed,
     * but only an indexed setter (as opposed to an array setter)
     * is available.</li>
     * <li>Does not support destination properties that are mapped,
     * but only a keyed setter (as opposed to a Map setter)
     * is available.</li>
     * <li>The desired property type of a mapped setter cannot be
     * determined (since Maps support any data type), so no conversion
     * will be performed.</li>
     * </ul>
     *
     * @param bean
     *            Bean on which setting is to be performed
     * @param name
     *            Property name (can be nested/indexed/mapped/combo)
     * @param value
     *            Value to be set
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     */
    public void copyProperty(final Object bean,String name,Object value) throws IllegalAccessException,InvocationTargetException{

        // Trace logging (if enabled)
        if (LOGGER.isTraceEnabled()){
            final StringBuilder sb = new StringBuilder("  copyProperty(");
            sb.append(bean);
            sb.append(", ");
            sb.append(name);
            sb.append(", ");
            if (value == null){
                sb.append("<NULL>");
            }else if (value instanceof String){
                sb.append((String) value);
            }else if (value instanceof String[]){
                final String[] values = (String[]) value;
                sb.append('[');
                for (int i = 0; i < values.length; i++){
                    if (i > 0){
                        sb.append(',');
                    }
                    sb.append(values[i]);
                }
                sb.append(']');
            }else{
                sb.append(value.toString());
            }
            sb.append(')');
            LOGGER.trace(sb.toString());
        }

        // Resolve any nested expression to get the actual target bean
        Object target = bean;
        final Resolver resolver = getPropertyUtils().getResolver();
        while (resolver.hasNested(name)){
            try{
                target = getPropertyUtils().getProperty(target, resolver.next(name));
                name = resolver.remove(name);
            }catch (final NoSuchMethodException e){
                return; // Skip this property setter
            }
        }
        if (LOGGER.isTraceEnabled()){
            LOGGER.trace("    Target bean = " + target);
            LOGGER.trace("    Target name = " + name);
        }

        // Declare local variables we will require
        final String propName = resolver.getProperty(name); // Simple name of target property
        Class<?> type = null; // Java type of target property
        final int index = resolver.getIndex(name); // Indexed subscript value (if any)
        final String key = resolver.getKey(name); // Mapped key value (if any)

        // Calculate the target property type
        if (target instanceof DynaBean){
            final DynaClass dynaClass = ((DynaBean) target).getDynaClass();
            final DynaProperty dynaProperty = dynaClass.getDynaProperty(propName);
            if (dynaProperty == null){
                return; // Skip this property setter
            }
            type = dynaPropertyType(dynaProperty, value);
        }else{
            PropertyDescriptor descriptor = null;
            try{
                descriptor = getPropertyUtils().getPropertyDescriptor(target, name);
                if (descriptor == null){
                    return; // Skip this property setter
                }
            }catch (final NoSuchMethodException e){
                return; // Skip this property setter
            }
            type = descriptor.getPropertyType();
            if (type == null){
                // Most likely an indexed setter on a POJB only
                if (LOGGER.isTraceEnabled()){
                    LOGGER.trace("    target type for property '" + propName + "' is null, so skipping ths setter");
                }
                return;
            }
        }
        if (LOGGER.isTraceEnabled()){
            LOGGER.trace("    target propName=" + propName + ", type=" + type + ", index=" + index + ", key=" + key);
        }

        // Convert the specified value to the required type and store it
        if (index >= 0){ // Destination must be indexed
            value = convertForCopy(value, type.getComponentType());
            try{
                getPropertyUtils().setIndexedProperty(target, propName, index, value);
            }catch (final NoSuchMethodException e){
                throw new InvocationTargetException(e, "Cannot set " + propName);
            }
        }else if (key != null){ // Destination must be mapped
            // Maps do not know what the preferred data type is,
            // so perform no conversions at all
            // FIXME - should we create or support a TypedMap?
            try{
                getPropertyUtils().setMappedProperty(target, propName, key, value);
            }catch (final NoSuchMethodException e){
                throw new InvocationTargetException(e, "Cannot set " + propName);
            }
        }else{ // Destination must be simple
            value = convertForCopy(value, type);
            try{
                getPropertyUtils().setSimpleProperty(target, propName, value);
            }catch (final NoSuchMethodException e){
                throw new InvocationTargetException(e, "Cannot set " + propName);
            }
        }

    }

    /**
     * <p>
     * Return the entire set of properties for which the specified bean
     * provides a read method. This map contains the to <code>String</code>
     * converted property values for all properties for which a read method
     * is provided (i.e. where the getReadMethod() returns non-null).
     * </p>
     *
     * <p>
     * This map can be fed back to a call to
     * <code>BeanUtils.populate()</code> to reconsitute the same set of
     * properties, modulo differences for read-only and write-only
     * properties, but only if there are no indexed properties.
     * </p>
     *
     * <p>
     * <strong>Warning:</strong> if any of the bean property implementations
     * contain (directly or indirectly) a call to this method then
     * a stack overflow may result. For example:
     * <code><pre>
     * class MyBean
     * {
     *    public Map getParameterMap()
     *    {
     *         BeanUtils.describe(this);
     *    }
     * }
     * </pre></code>
     * will result in an infinite regression when <code>getParametersMap</code>
     * is called. It is recommended that such methods are given alternative
     * names (for example, <code>parametersMap</code>).
     * </p>
     * 
     * @param bean
     *            Bean whose properties are to be extracted
     * @return Map of property descriptors
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     * @throws NoSuchMethodException
     *             if an accessor method for this
     *             property cannot be found
     */
    public Map<String, String> describe(final Object bean) throws IllegalAccessException,InvocationTargetException,NoSuchMethodException{

        if (bean == null){
            //            return (Collections.EMPTY_MAP);
            return (new java.util.HashMap<>());
        }

        if (LOGGER.isDebugEnabled()){
            LOGGER.debug("Describing bean: " + bean.getClass().getName());
        }

        final Map<String, String> description = new HashMap<>();
        if (bean instanceof DynaBean){
            final DynaProperty[] descriptors = ((DynaBean) bean).getDynaClass().getDynaProperties();
            for (DynaProperty descriptor : descriptors){
                final String name = descriptor.getName();
                description.put(name, getProperty(bean, name));
            }
        }else{
            final PropertyDescriptor[] descriptors = getPropertyUtils().getPropertyDescriptors(bean);
            final Class<?> clazz = bean.getClass();
            for (PropertyDescriptor descriptor : descriptors){
                final String name = descriptor.getName();
                getPropertyUtils();
                if (PropertyUtilsBean.getReadMethod(clazz, descriptor) != null){
                    description.put(name, getProperty(bean, name));
                }
            }
        }
        return (description);

    }

    /**
     * Return the value of the specified array property of the specified
     * bean, as a String array.
     *
     * @param bean
     *            Bean whose property is to be extracted
     * @param name
     *            Name of the property to be extracted
     * @return The array property value
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     * @throws NoSuchMethodException
     *             if an accessor method for this
     *             property cannot be found
     */
    public String[] getArrayProperty(final Object bean,final String name)
                    throws IllegalAccessException,InvocationTargetException,NoSuchMethodException{

        final Object value = getPropertyUtils().getProperty(bean, name);
        if (value == null){
            return (null);
        }else if (value instanceof Collection){
            final ArrayList<String> values = new ArrayList<>();
            for (final Object item : (Collection<?>) value){
                if (item == null){
                    values.add(null);
                }else{
                    // convert to string using convert utils
                    values.add(getConvertUtils().convert(item));
                }
            }
            return (values.toArray(new String[values.size()]));
        }else if (value.getClass().isArray()){
            final int n = Array.getLength(value);
            final String[] results = new String[n];
            for (int i = 0; i < n; i++){
                final Object item = Array.get(value, i);
                if (item == null){
                    results[i] = null;
                }else{
                    // convert to string using convert utils
                    results[i] = getConvertUtils().convert(item);
                }
            }
            return (results);
        }else{
            final String[] results = new String[1];
            results[0] = getConvertUtils().convert(value);
            return (results);
        }

    }

    /**
     * Return the value of the specified indexed property of the specified
     * bean, as a String. The zero-relative index of the
     * required value must be included (in square brackets) as a suffix to
     * the property name, or <code>IllegalArgumentException</code> will be
     * thrown.
     *
     * @param bean
     *            Bean whose property is to be extracted
     * @param name
     *            <code>propertyname[index]</code> of the property value
     *            to be extracted
     * @return The indexed property's value, converted to a String
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     * @throws NoSuchMethodException
     *             if an accessor method for this
     *             property cannot be found
     */
    public String getIndexedProperty(final Object bean,final String name)
                    throws IllegalAccessException,InvocationTargetException,NoSuchMethodException{

        final Object value = getPropertyUtils().getIndexedProperty(bean, name);
        return (getConvertUtils().convert(value));

    }

    /**
     * Return the value of the specified indexed property of the specified
     * bean, as a String. The index is specified as a method parameter and
     * must *not* be included in the property name expression
     *
     * @param bean
     *            Bean whose property is to be extracted
     * @param name
     *            Simple property name of the property value to be extracted
     * @param index
     *            Index of the property value to be extracted
     * @return The indexed property's value, converted to a String
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     * @throws NoSuchMethodException
     *             if an accessor method for this
     *             property cannot be found
     */
    public String getIndexedProperty(final Object bean,final String name,final int index)
                    throws IllegalAccessException,InvocationTargetException,NoSuchMethodException{

        final Object value = getPropertyUtils().getIndexedProperty(bean, name, index);
        return (getConvertUtils().convert(value));

    }

    /**
     * Return the value of the specified indexed property of the specified
     * bean, as a String. The String-valued key of the required value
     * must be included (in parentheses) as a suffix to
     * the property name, or <code>IllegalArgumentException</code> will be
     * thrown.
     *
     * @param bean
     *            Bean whose property is to be extracted
     * @param name
     *            <code>propertyname(index)</code> of the property value
     *            to be extracted
     * @return The mapped property's value, converted to a String
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     * @throws NoSuchMethodException
     *             if an accessor method for this
     *             property cannot be found
     */
    public String getMappedProperty(final Object bean,final String name)
                    throws IllegalAccessException,InvocationTargetException,NoSuchMethodException{

        final Object value = getPropertyUtils().getMappedProperty(bean, name);
        return (getConvertUtils().convert(value));

    }

    /**
     * Return the value of the specified mapped property of the specified
     * bean, as a String. The key is specified as a method parameter and
     * must *not* be included in the property name expression
     *
     * @param bean
     *            Bean whose property is to be extracted
     * @param name
     *            Simple property name of the property value to be extracted
     * @param key
     *            Lookup key of the property value to be extracted
     * @return The mapped property's value, converted to a String
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     * @throws NoSuchMethodException
     *             if an accessor method for this
     *             property cannot be found
     */
    public String getMappedProperty(final Object bean,final String name,final String key)
                    throws IllegalAccessException,InvocationTargetException,NoSuchMethodException{

        final Object value = getPropertyUtils().getMappedProperty(bean, name, key);
        return (getConvertUtils().convert(value));

    }

    /**
     * Return the value of the (possibly nested) property of the specified
     * name, for the specified bean, as a String.
     *
     * @param bean
     *            Bean whose property is to be extracted
     * @param name
     *            Possibly nested name of the property to be extracted
     * @return The nested property's value, converted to a String
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws IllegalArgumentException
     *             if a nested reference to a
     *             property returns null
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     * @throws NoSuchMethodException
     *             if an accessor method for this
     *             property cannot be found
     */
    public String getNestedProperty(final Object bean,final String name)
                    throws IllegalAccessException,InvocationTargetException,NoSuchMethodException{

        final Object value = getPropertyUtils().getProperty(bean, name);
        return getConvertUtils().convert(value);

    }

    /**
     * Return the value of the specified property of the specified bean,
     * no matter which property reference format is used, as a String.
     *
     * @param bean
     *            Bean whose property is to be extracted
     * @param name
     *            Possibly indexed and/or nested name of the property
     *            to be extracted
     * @return The property's value, converted to a String
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     * @throws NoSuchMethodException
     *             if an accessor method for this
     *             property cannot be found
     */
    public String getProperty(final Object bean,final String name)
                    throws IllegalAccessException,InvocationTargetException,NoSuchMethodException{

        return (getNestedProperty(bean, name));

    }

    /**
     * Return the value of the specified simple property of the specified
     * bean, converted to a String.
     *
     * @param bean
     *            Bean whose property is to be extracted
     * @param name
     *            Name of the property to be extracted
     * @return The property's value, converted to a String
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     * @throws NoSuchMethodException
     *             if an accessor method for this
     *             property cannot be found
     */
    public String getSimpleProperty(final Object bean,final String name)
                    throws IllegalAccessException,InvocationTargetException,NoSuchMethodException{

        final Object value = getPropertyUtils().getSimpleProperty(bean, name);
        return (getConvertUtils().convert(value));

    }

    /**
     * <p>
     * Populate the JavaBeans properties of the specified bean, based on
     * the specified name/value pairs. This method uses Java reflection APIs
     * to identify corresponding "property setter" method names, and deals
     * with setter arguments of type <code>String</code>, <code>boolean</code>,
     * <code>int</code>, <code>long</code>, <code>float</code>, and
     * <code>double</code>. In addition, array setters for these types (or the
     * corresponding primitive types) can also be identified.
     * </p>
     *
     * <p>
     * The particular setter method to be called for each property is
     * determined using the usual JavaBeans introspection mechanisms. Thus,
     * you may identify custom setter methods using a BeanInfo class that is
     * associated with the class of the bean itself. If no such BeanInfo
     * class is available, the standard method name conversion ("set" plus
     * the capitalized name of the property in question) is used.
     * </p>
     *
     * <p>
     * <strong>NOTE</strong>: It is contrary to the JavaBeans Specification
     * to have more than one setter method (with different argument
     * signatures) for the same property.
     * </p>
     *
     * <p>
     * <strong>WARNING</strong> - The logic of this method is customized
     * for extracting String-based request parameters from an HTTP request.
     * It is probably not what you want for general property copying with
     * type conversion. For that purpose, check out the
     * <code>copyProperties()</code> method instead.
     * </p>
     *
     * @param bean
     *            JavaBean whose properties are being populated
     * @param properties
     *            Map keyed by property name, with the
     *            corresponding (String or String[]) value(s) to be set
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     */
    public void populate(final Object bean,final Map<String, ? extends Object> properties)
                    throws IllegalAccessException,InvocationTargetException{

        // Do nothing unless both arguments have been specified
        if ((bean == null) || (properties == null)){
            return;
        }
        if (LOGGER.isDebugEnabled()){
            LOGGER.debug("BeanUtils.populate(" + bean + ", " + properties + ")");
        }

        // Loop through the property name/value pairs to be set
        for (final Map.Entry<String, ? extends Object> entry : properties.entrySet()){
            // Identify the property name and value(s) to be assigned
            final String name = entry.getKey();
            if (name == null){
                continue;
            }

            // Perform the assignment for this property
            setProperty(bean, name, entry.getValue());

        }

    }

    /**
     * <p>
     * Set the specified property value, performing type conversions as
     * required to conform to the type of the destination property.
     * </p>
     *
     * <p>
     * If the property is read only then the method returns
     * without throwing an exception.
     * </p>
     *
     * <p>
     * If <code>null</code> is passed into a property expecting a primitive value,
     * then this will be converted as if it were a <code>null</code> string.
     * </p>
     *
     * <p>
     * <strong>WARNING</strong> - The logic of this method is customized
     * to meet the needs of <code>populate()</code>, and is probably not what
     * you want for general property copying with type conversion. For that
     * purpose, check out the <code>copyProperty()</code> method instead.
     * </p>
     *
     * <p>
     * <strong>WARNING</strong> - PLEASE do not modify the behavior of this
     * method without consulting with the Struts developer community. There
     * are some subtleties to its functionality that are not documented in the
     * Javadoc description above, yet are vital to the way that Struts utilizes
     * this method.
     * </p>
     *
     * @param bean
     *            Bean on which setting is to be performed
     * @param name
     *            Property name (can be nested/indexed/mapped/combo)
     * @param value
     *            Value to be set
     *
     * @throws IllegalAccessException
     *             if the caller does not have
     *             access to the property accessor method
     * @throws InvocationTargetException
     *             if the property accessor method
     *             throws an exception
     */
    public void setProperty(final Object bean,String name,final Object value) throws IllegalAccessException,InvocationTargetException{

        // Trace logging (if enabled)
        if (LOGGER.isTraceEnabled()){
            final StringBuilder sb = new StringBuilder("  setProperty(");
            sb.append(bean);
            sb.append(", ");
            sb.append(name);
            sb.append(", ");
            if (value == null){
                sb.append("<NULL>");
            }else if (value instanceof String){
                sb.append((String) value);
            }else if (value instanceof String[]){
                final String[] values = (String[]) value;
                sb.append('[');
                for (int i = 0; i < values.length; i++){
                    if (i > 0){
                        sb.append(',');
                    }
                    sb.append(values[i]);
                }
                sb.append(']');
            }else{
                sb.append(value.toString());
            }
            sb.append(')');
            LOGGER.trace(sb.toString());
        }

        // Resolve any nested expression to get the actual target bean
        Object target = bean;
        final Resolver resolver = getPropertyUtils().getResolver();
        while (resolver.hasNested(name)){
            try{
                target = getPropertyUtils().getProperty(target, resolver.next(name));
                if (target == null){ // the value of a nested property is null
                    return;
                }
                name = resolver.remove(name);
            }catch (final NoSuchMethodException e){
                return; // Skip this property setter
            }
        }
        if (LOGGER.isTraceEnabled()){
            LOGGER.trace("    Target bean = " + target);
            LOGGER.trace("    Target name = " + name);
        }

        // Declare local variables we will require
        final String propName = resolver.getProperty(name); // Simple name of target property
        Class<?> type = null; // Java type of target property
        final int index = resolver.getIndex(name); // Indexed subscript value (if any)
        final String key = resolver.getKey(name); // Mapped key value (if any)

        // Calculate the property type
        if (target instanceof DynaBean){
            final DynaClass dynaClass = ((DynaBean) target).getDynaClass();
            final DynaProperty dynaProperty = dynaClass.getDynaProperty(propName);
            if (dynaProperty == null){
                return; // Skip this property setter
            }
            type = dynaPropertyType(dynaProperty, value);
            if (index >= 0 && List.class.isAssignableFrom(type)){
                type = Object.class;
            }
        }else if (target instanceof Map){
            type = Object.class;
        }else if (target != null && target.getClass().isArray() && index >= 0){
            type = Array.get(target, index).getClass();
        }else{
            PropertyDescriptor descriptor = null;
            try{
                descriptor = getPropertyUtils().getPropertyDescriptor(target, name);
                if (descriptor == null){
                    return; // Skip this property setter
                }
            }catch (final NoSuchMethodException e){
                return; // Skip this property setter
            }
            if (descriptor instanceof MappedPropertyDescriptor){
                if (((MappedPropertyDescriptor) descriptor).getMappedWriteMethod() == null){
                    if (LOGGER.isDebugEnabled()){
                        LOGGER.debug("Skipping read-only property");
                    }
                    return; // Read-only, skip this property setter
                }
                type = ((MappedPropertyDescriptor) descriptor).getMappedPropertyType();
            }else if (index >= 0 && descriptor instanceof IndexedPropertyDescriptor){
                if (((IndexedPropertyDescriptor) descriptor).getIndexedWriteMethod() == null){
                    if (LOGGER.isDebugEnabled()){
                        LOGGER.debug("Skipping read-only property");
                    }
                    return; // Read-only, skip this property setter
                }
                type = ((IndexedPropertyDescriptor) descriptor).getIndexedPropertyType();
            }else if (index >= 0 && List.class.isAssignableFrom(descriptor.getPropertyType())){
                type = Object.class;
            }else if (key != null){
                if (descriptor.getReadMethod() == null){
                    if (LOGGER.isDebugEnabled()){
                        LOGGER.debug("Skipping read-only property");
                    }
                    return; // Read-only, skip this property setter
                }
                type = (value == null) ? Object.class : value.getClass();
            }else{
                if (descriptor.getWriteMethod() == null){
                    if (LOGGER.isDebugEnabled()){
                        LOGGER.debug("Skipping read-only property");
                    }
                    return; // Read-only, skip this property setter
                }
                type = descriptor.getPropertyType();
            }
        }

        // Convert the specified value to the required type
        Object newValue = null;
        if (type.isArray() && (index < 0)){ // Scalar value into array
            if (value == null){
                final String[] values = new String[1];
                values[0] = null;
                newValue = getConvertUtils().convert(values, type);
            }else if (value instanceof String){
                newValue = getConvertUtils().convert(value, type);
            }else if (value instanceof String[]){
                newValue = getConvertUtils().convert((String[]) value, type);
            }else{
                newValue = convert(value, type);
            }
        }else if (type.isArray()){ // Indexed value into array
            if (value instanceof String || value == null){
                newValue = getConvertUtils().convert((String) value, type.getComponentType());
            }else if (value instanceof String[]){
                newValue = getConvertUtils().convert(((String[]) value)[0], type.getComponentType());
            }else{
                newValue = convert(value, type.getComponentType());
            }
        }else{ // Value into scalar
            if (value instanceof String){
                newValue = getConvertUtils().convert((String) value, type);
            }else if (value instanceof String[]){
                newValue = getConvertUtils().convert(((String[]) value)[0], type);
            }else{
                newValue = convert(value, type);
            }
        }

        // Invoke the setter method
        try{
            getPropertyUtils().setProperty(target, name, newValue);
        }catch (final NoSuchMethodException e){
            throw new InvocationTargetException(e, "Cannot set " + propName);
        }

    }

    /**
     * Gets the <code>ConvertUtilsBean</code> instance used to perform the conversions.
     *
     * @return The ConvertUtils bean instance
     */
    public ConvertUtilsBean getConvertUtils(){
        return convertUtilsBean;
    }

    /**
     * Gets the <code>PropertyUtilsBean</code> instance used to access properties.
     *
     * @return The ConvertUtils bean instance
     */
    public PropertyUtilsBean getPropertyUtils(){
        return propertyUtilsBean;
    }

    /**
     * <p>
     * Convert the value to an object of the specified class (if
     * possible).
     * </p>
     *
     * @param value
     *            Value to be converted (may be null)
     * @param type
     *            Class of the value to be converted to
     * @return The converted value
     *
     * @throws ConversionException
     *             if thrown by an underlying Converter
     * @since 1.8.0
     */
    protected Object convert(final Object value,final Class<?> type){
        final Converter converter = getConvertUtils().lookup(type);
        if (converter != null){
            LOGGER.trace("        USING CONVERTER " + converter);
            return converter.convert(type, value);
        }
        return value;
    }

    /**
     * Performs a type conversion of a property value before it is copied to a target
     * bean. This method delegates to {@link #convert(Object, Class)}, but <b>null</b>
     * values are not converted. This causes <b>null</b> values to be copied verbatim.
     *
     * @param value
     *            the value to be converted and copied
     * @param type
     *            the target type of the conversion
     * @return the converted value
     */
    private Object convertForCopy(final Object value,final Class<?> type){
        return (value != null) ? convert(value, type) : value;
    }

    /**
     * Determines the type of a {@code DynaProperty}. Here a special treatment
     * is needed for mapped properties.
     *
     * @param dynaProperty
     *            the property descriptor
     * @param value
     *            the value object to be set for this property
     * @return the type of this property
     */
    private static Class<?> dynaPropertyType(final DynaProperty dynaProperty,final Object value){
        if (!dynaProperty.isMapped()){
            return dynaProperty.getType();
        }
        return (value == null) ? String.class : value.getClass();
    }
}
